Gentlemen,
Maybe this question has been raised before.
What are the reasons for the differences in voltage levels between the US and Europe - 4.16 kV (US) vs. 3.3 kV (Euro.) and 7.2kV (US) vs. 6.6 kV (Euro.)? Does it have anything to do with the 50 Hz. vs. 60 Hz. frequency differences...
Gentlemen,
Our coal mining company is setting up training facilities to train our mine electricians on how to safely troubleshoot our equipment. The supply voltages to this equipment would be either 480 volts (3 phase) or 950 volts (3 phase).
When being used underground, our equipment is...
Gentlemen,
There should be a relationship between short circuit MVA at any point in a distribution system and the voltage drop that occurs when a motor is started at that same point in the system. Is there a straight forward relationship between the two or does the voltage drop also depend...
We have an installation where we may want to run two AC three phase generators from one common driver. The generators will then be connected in parallel electrically. Since they are both driven from a common driver, they are also in parallel mechanically. I have heard that there may be some...
First - I hope that everyone is enjoyng the Holiday Season and spending some relaxing time with family and friends.
We manufacture gearing and couplings to coupler diesel engines to three phase generators. The generator size is 2- 2.5 MW. The generators are 60 Hz, and the output voltage...
If I wanted to install a resistance grounded system (480 volt or 4160 volt), I know that there is a theoretical maximum resistance that is recommended. If I remember correctly, it is based on the system charging current. Can anyone help me with this issue?
Regards,
Raisinbran
I am looking for possible causes of damage to the gears/bearings in a speed-change gearcase that couples a large diesel engine (2000 kW) to a 2700 kVA generator. This system is connected to other generators and the utility thru a set of circuit breakers. One theory is that the gen-set circuit...
Gentlemen,
My background is Electrical Engineering, so excuse me if I don't use the correct terminology.
We use several helical gearboxes at our plant. They are parallel shaft, single reduction units. Each shaft is approx. 6 inches in diameter. Input shaft speed is 1800 RPM. Each shaft is...
Hello All,
My background is electrical engineering, so I apologize if I do not understand the proper terminology.
We have had a gearing failure and there is some dispute as to what has caused the failure. The gears are straight spur gears and reduce the speed from 1800 rpm to around 500 rpm in...
We have a situation where it would be advantageous to run a higher voltage power line (34.5 kV)underneath of a lower voltage (4.16 kV)power line. Both lines are on poles, but serve only our needs - mining. Assuming that we maintain adequate clearances, are there any rules/standards to prevent...
When the taps of a transformer are raised (or lowered), does the available short circuit MVA at the transformer secondary raise (or lower) or stay the same as calculated at nominal tap settings?
Raisinbran
Looking to install a 4160 volt system dedicated to a 3000 HP motor. Total cable length is less than 200 feet. Existing transformer secondary is delta connected. Contractor wants to install a resistance grounded (15 ampere limit) using a zig-zag grounding transformer. Question: Do you fuse...
I already have an opinion on this issue, but there are a lot of smart people on this forum with a lot more experience than I will ever have, so I thought that I would ask.
We have an inclined conveyor that failed to hold under load. The conveyor was stopped due to a normal sequence stop. The...
In the mining industry, motors that can satisfactorily move the load have difficulty starting the load because of voltage drops in the system. These particular motors are mechanically connected to the load using fluid couplers to take advantage of the motor breakdown torque. The motors are...
We operate a 3500 foot long inclined belt conveyor. The conveyor is powered by two 2500 HP induction motors, and the motors are coupled to the drive through fixed fill fluid couplers. For some reason, during a "routine" stop, the rollbacks failed to engage and the loaded conveyor rolled...
